System and process for injecting catalyst and/or additives into a fluidized catalytic cracking unit

ABSTRACT

A preferred embodiment of a system for loading catalyst and/or additives into a fluidized catalytic cracking unit includes a bin for storing at least one of the catalyst and/or additives, and a loading unit in fluid communication with the storage bin and the fluidized catalytic cracking unit on a selective basis. The loading unit is capable of being evacuated so that a resulting vacuum within the loading unit draws the catalyst and/or additive from the bin. The loading unit is also capable of being pressurized so that the catalyst and/or additive is transferred from the loading unit to the fluidized catalytic cracking unit.

CROSS REFERENCE OF THE INVENTION

This application is a divisional of U.S. patent application Ser. No.10/806,563 filed on Mar. 23, 2004, the content of which is herebyincorporated by reference as if set forth in its entirety herein.

FIELD OF THE INVENTION

The present invention relates to equipment used in fluidized catalyticcracking (FCC) operations and, more particularly, to systems andprocesses for injecting catalyst and/or additives into equipment unitsemployed to conduct FCC operations.

BACKGROUND OF THE INVENTION

FCC units commonly include a circulating inventory of bulk catalyst. Thebulk catalyst is typically used to perform a primary function, such asproducing naptha from petroleum feedstock, the naptha being furtherprocessed into gasoline. Additives, which are often in the samefluidizable and particulated form as the catalyst, are often introducedinto the circulating inventory of bulk catalyst to perform a secondaryfunction such as reducing certain types of emissions, e.g., SOx or NOx,produced by the FCC unit. These emissions are produced in the catalystregenerator of the FCC unit where coke deposits from the crackedpetroleum are burned off and the regenerated catalyst returned to thecirculating catalyst inventory, These additives are usually introducedinto the regenerator using an injection device commonly referred to as a“loader.” Loaders are also used to add catalyst to the bulk inventory asadditional catalyst becomes necessary due to factors such as attritionand deactivation.

Loaders used for catalyst and/or additive injection typically comprise atransfer pot, and a storage hopper or silo located above or proximatethe transfer pot. The catalyst and/or additive is usually transferred tothe storage hopper from a storage bin using a suitable technique such asvacuum transfer. During operation of the loader, a predetermined amountof catalyst and/or additive can be metered to the transfer pot from thestorage hopper. The transfer pot can subsequently be pressurized, andthe catalyst and/or additive can be injected into the regenerator inresponse to the pressure within the transfer pot. This process isusually repeated on a cyclical basis.

The amount of catalyst metered to the transfer pot and injected duringeach cycle is usually small in comparison to the overall volume of thestorage hopper. In other words, a relatively large volume of catalystand/or additive is typically stored in the hopper so that relativelysmall doses of the catalyst and/or additive can be metered to thetransfer pot during each cycle. A typical storage hopper is relativelylarge due to the need to accommodate a large amount of additive orcatalyst therein. For example, a typical storage hopper can have adiameter of five feet or more, and height of fifteen feet or more.

The relatively large size of conventional storage hoppers can limit thenumber of suitable locations in which the loader can be installed. Thischaracteristic can be particularly disadvantageous at a refinery, wherespace can be and often is limited. The need for a relatively large areato accommodate the loader (and in particular the storage hopper) canthus necessitate placing the loader in a less than optimal location.

Moreover, the loader can only be used to inject one type of catalystand/or additive at a time, due to the need for a dedicated storagehopper for each type of catalyst and/or additive. In other words, thetransfer pot can only inject the catalyst and/or additive stored in itsassociated hopper, until the catalyst and/or additive is replaced withanother type of catalyst and/or additive. Hence, loading different typescatalyst and/or additives on simultaneous or near-simultaneous (back toback) basis can only be accomplished using multiple loaders. Eachadditional loader requires additional outlays of time, labor, and moneyto purchase, install, operate, and maintain. Moreover, each loaderconsumes potentially valuable space within the refinery.

The storage hopper may be pressurized in some applications to facilitatetransfer of the catalyst and/or additive to the transfer pot. Thepressurized air within the hopper can adversely affect the measurementsthat provide and indication of how much catalyst and/or additive hasbeen added to the transfer pot. Also, the catalyst and/or additive maybe exposed to pressurized air from the refinery (commonly referred to as“plant air”) while it is being transferred to, or stored in the hopper.Plant air often contains moisture or other contaminates that canadversely affect the catalyst and/or additive.

SUMMARY OF THE INVENTION

A preferred embodiment of a system for injecting catalyst and/oradditives into a fluidized catalytic cracking unit comprises a dustcollector in fluid communication with a storage bin holding one of thecatalyst and/or additives, and a vacuum producer in fluid communicationwith the dust collector so that the vacuum producer generates a vacuumwithin the dust collector that draws the one of the catalyst and/oradditives into the dust collector.

The system also comprises a transfer pot for receiving the one of thecatalyst and/or additives from the dust collector. The transfer pot isin fluid communication with the fluidized catalytic cracking unit and asource of pressurized air so that the one of the catalyst and/oradditives is transferred to the fluidized catalytic cracking unit inresponse to a pressure differential between the transfer pot and thefluidized catalytic cracking unit.

A preferred embodiment of a system for loading catalyst and/or additivesinto a fluidized catalytic cracking unit comprises a bin for storing atleast one of the catalyst and/or additives, and a loading unit in fluidcommunication with the storage bin and the fluidized catalytic crackingunit on a selective basis. The loading unit is capable of beingevacuated so that a resulting vacuum within the loading unit draws theat least one of the catalyst and/or additives from the bin, and theloading unit is capable of being pressurized so that the least one ofthe catalyst and/or additives is transferred from the loading unit tothe fluidized catalytic cracking unit.

Another preferred embodiment of a system for loading catalyst and/oradditives into a fluidized catalytic cracking unit comprises a first binfor storing a first of the catalyst and/or additives, a second bin forstoring a second of the catalyst and/or additives, and a loading unit influid communication with the first and second bins and the fluidizedcatalytic cracking unit. The system also comprises a first valve forisolating the first bin from the loading unit on a selective basis, asecond valve for isolating the second bin from the loading unit on aselective basis, and a third valve for isolating the second bin from thefluidized catalytic cracking unit on a selective basis.

A preferred embodiment of a system for introducing catalyst and/oradditives into a fluidized catalytic cracking unit comprises a dustcollecting means in fluid communication with a storage bin holding oneof the catalyst and/or additives, and a vacuum producing means in fluidcommunication with the dust collecting means so that the vacuumproducing means draws the one of the catalyst and/or additives into thedust collecting means. The system also comprises a means for receivingthe one of the catalyst and/or additives from the dust collecting meansand injecting the one of the catalyst and/or additives into thefluidized catalytic cracking unit.

A preferred process for introducing catalyst and/or additives into afluidized catalytic cracking unit comprises generating a vacuum within aloading unit, drawing one of the catalyst and/or additives from astorage bin and into the loading unit in response to the vacuum,pressurizing the loading unit, and injecting the one of the catalystand/or additives into the fluidized catalytic cracking unit in responseto the pressurization of the loading unit.

A preferred process for loading catalyst and/or additives into afluidized catalytic cracking unit comprises storing at least one of thecatalyst and/or additives at a first location, vacuuming the at leastone of the catalyst and/or additives into a loading unit positioned at asecond location, and injecting the at least one of a catalyst and/oradditives into the fluidized catalytic cracking unit from the loadingunit.

A preferred embodiment of a system for introducing one or moreparticulate substances into a fluid stream comprises a dust collectingmeans in fluid communication with at least one storage bin holding theone or more particulate substances. The system also comprises a vacuumproducing means in fluid communication with the dust collecting means sothat the one or more particulate substances is drawn into the dustcollecting means from the at least one storage bin by a vacuum. Thesystem further comprises a means for receiving the one or moreparticulate substances from the dust collecting means and injecting theone or more particulate substances into the fluid stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofa preferred embodiment, are better understood when read in conjunctionwith the appended diagrammatic drawings. For the purpose of illustratingthe invention, the drawings show an embodiment that is presentlypreferred. The invention is not limited, however, to the specificinstrumentalities disclosed in the drawings. In the drawings:

FIG. 1 is a schematic side view of a preferred embodiment of a systemfor injecting catalyst and/or additives into an FCC unit, showing a dustcollector and a transfer pot of the system longitudinal cross section;

FIG. 2 is a diagrammatic side view of the system shown in FIG. 1;

FIG. 3 is a diagrammatic side view of the system shown in FIGS. 1 and 2,from a perspective rotated approximately 180 degrees from theperspective of FIG. 2;

FIG. 4 is a diagrammatic side view of the system shown in FIGS. 1-3,from a perspective rotated approximately 90 degrees from the perspectiveof FIG. 2;

FIG. 5 is a magnified view of the area designated “A” in FIG. 3;

FIG. 6 is a block diagram depicting a control system of the system shownin FIGS. 1-5;

FIG. 7 is a flow diagram depicting operation of the system shown inFIGS. 1-6; and

FIG. 8 is a top view of a manifold for use with an alternativeembodiment of the system shown in FIGS. 1-6.

DESCRIPTION OF REFERRED EMBODIMENTS

A preferred embodiment of a system 10 for injecting catalyst and/oradditives into an FCC unit is depicted in FIGS. 1-6. The loading system10 forms part of an overall system 11 for storing and loading catalystand/or additives. The system 11 includes the loading system 10, and oneor more storage bins 37.

The loading system 10 comprises a loading unit 14 having a dustcollector 16 and an adjoining transfer pot 18. The loading system 10, asdiscussed in detail below, produces a vacuum that draws catalyst and/oradditive from the storage bins 37 and into the dust collector 16. Thecatalyst and/or additive falls to the bottom of the dust collector 16and into the transfer pot 18. The transfer pot 18 is subsequentlypressurized, and the catalyst and/or additive is injected into aregenerator of the FCC unit in response to the pressure within thetransfer pot 18.

The loading unit 14 can be housed within a cabinet 19 (see FIGS. 2-4).(The cabinet 19 is shown in the figures with its side panels removed,for clarity.) The loading unit 14 is preferably supported by a pluralityof legs 20 affixed to the transfer pot 18.

The dust collector 16 comprises a sidewall 17. The sidewall 17 should beof a suitable strength and thickness to withstand the presence of avacuum within the dust collector 16.

The cross section and overall shape of the dust collector 16 can vary.The dust collector 16 depicted in the figures has a substantiallycylindrical upper portion 16 a, and a substantially conical lowerportion 16 b that adjoins the upper portion 16 a. An opening 23 isformed in the center of the lower portion 16 b (see FIG. 1). A screen 24is positioned across the lower portion 16 b. In other embodiments, thecross section of the upper portion 16 a and the lower portion 16 b canbe square or rectangular, and the overall shape can be in the form of asquare or rectangular column. (Directional terms such as “upper,”“lower,” etc. are used herein with reference to the componentorientations depicted in FIG. 1. These terms are used for exemplarypurposes only, and are not intended to limit the scope of the appendedclaims.)

The dust collector 16 also includes a cover 25. The cover 25 mates withan upper edge of the sidewall 17. A gasket is positioned between thecover 25 and the sidewall 17 to form a substantially airtight sealtherebetween. The sidewall 17 and the cover 25 define an internal volume26 within the dust collector 16 (see FIG. 1).

The dust collector 16 also comprises a suitable filter 32 (see FIG. 1).The filter 32 can be, for example, a Mactiflo model E376094 filter.

The filter 32 is mounted within the upper portion 16 a of the dustcollector 16. The sidewall preferably includes a hatch 33 to provideaccess to the interior of the upper portion 16 a (and the filter 32)(see FIGS. 1 and 4). The hatch 33 is preferably secured the sidewall 17of the dust collector 16 using brackets 34 that permit the hatch 33 tobe removed with a minimal expenditure of time and effort, therebyfacilitating replacement of the filter 32 with a minimum of time andeffort. Alternative embodiments of the loading system 10 can be equippedwith more than one of the filters 32.

The system 10 also comprises suitable vacuum producer 30 (see FIGS. 1and 2). For example, the vacuum producer can be an Empire two-inchVacutran S150 vacuum producer.

The vacuum producer 30 is mounted within the cabinet 19 (see FIG. 2).The vacuum producer 30 is preferably mounted separately from the loadingunit 14. The vacuum producer 30 is in fluid communication with thefilter 32 by way of a hose 35.

The vacuum producer 30 is in fluid communication with a suitable sourceof pressurized air (not shown). (The source of pressurized air can bethe plant air typically available at refineries.) The flow ofpressurized air into the vacuum producer 30 can be regulated by asuitable valve 36 having an actuator 36 a (see FIG. 1).

The vacuum producer 30 can operate in a manner commonly known to thoseskilled in the art of vacuum-chamber design. In particular, opening thevalve 36 permits the pressurized air to flow through the vacuum producer30. The flow of pressurized air through the vacuum producer 30 causesthe vacuum producer 30 to draw air from the internal volume 26 of thedust collector 16, thereby generating a vacuum within the internalvolume 26. (The vacuum producer 30 draws the air through the filter 32,thereby causing the dust collector 16 to collect the dust generated bythe flow of catalyst and/or additive into the dust collector 16.) Therespective directions of various airflows within the loading system 10are denoted by arrows 39 in FIG. 1.

The loading system 10 draws catalyst and/or additive from storage binsin response to the vacuum within the internal volume 26. In particular,the dust collector 16 is in fluid communication with storage bins 37(see FIG. 1). The storage bins 37 hold catalyst and/or additives to beinjected into the FCC unit. The storage bins 37 can be, for example, theshipping containers used to transport the catalyst and/or additives tothe refinery at which the loading system 10 is installed.

Each storage bin 37 is coupled to the dust collector 16 by acorresponding hose (or pipe) 38. A suitable valve 42 having an actuator42 a is located between each hose 38 and the dust collector 16. Eachvalve 42 isolates its associated storage bin 37 from the dust collector16 on a selective basis. The valves 42 are installed on the upperportion 16 a of the dust collector 16, and are in fluid communicationwith the internal volume 26 by way of corresponding openings formed inthe upper portion 16 a of the dust collector 16. (The hoses 38 andvalves 42 thus form part of the system 11 for storing and loadingcatalyst and/or additives).

The hoses 38 can be coupled to the upper portion 16 a by way of a commonmanifold 74 in alternative embodiments, as shown in FIG. 8.

The hoses 38 are preferably equipped with fittings that permit the hoses38 to be readily removed from the dust collector 16 (or the manifold 74)and the storage bins 37.

Opening one of the valves 42 permits catalyst and/or additive to bedrawn from the associated storage bin 37 by way of the associated hose38, in response to the vacuum within the internal volume 26. Thecatalyst and/or additive is thus drawn directly from the storage bin 37and into the loading system 10, without a need to load the catalystand/or additive into a storage hopper.

The loading system 10 is depicted as being equipped with three sets ofthe valves 42 and hoses 38, for exemplary purposes only. Alternativeembodiments can be equipped with more or less than three valves 42 andthree hoses 38, and can draw catalyst and/or additive from more or lessthan three of the storage bins 37.

The storage bins 37 can be positioned at a location remote from theloading system 10. For example, the storage bins 37 can be located up totwenty feet from the loading system 10. (The maximum distance betweenthe loading system 10 and the storage bins 37 is application dependent,and can vary with factors such as the capacity of the vacuum producer30, the diameter of the hoses 38, etc. A particular value for thisparameter is specified for exemplary purposes only.)

The dust collector 16 preferably includes three pipe guides 40. Eachpipe guide 40 is in fluid communication with an associated one of thehoses 38.

The catalyst and/or additive drawn into the internal volume 26 by way ofone of the pipe guides 40. The pipe guides 40 discharge the catalyst oradditive proximate into the internal volume 26, proximate the screen 24.

It should be noted that the depiction of the system 11 in FIG. 1 isschematic in nature, and the relative positions of the various hoses,piping, etc. of the system 11 can be different than those depicted inFIG. 1. For example, the openings formed in the upper portion 16 a ofthe dust collector 16 to accommodate the hoses 38 can be positionedaround the circumference of the upper portion 16 a, in lieu of thevertical arrangement depicted in FIG. 1.

The catalyst or additive drops toward the bottom of the dust collector16, i.e., toward the lower portion 16 b, after being discharged form thepipe guide 40 due to gravity. The catalyst and/or additive passesthrough the screen 24 as it drops (see FIG. 1). The mesh of the screen24 is preferably chosen to block the passage of relatively large clumpsor catalyst and/or additive (or foreign objects), while permittingrelatively fine granules of catalyst and/or additive to flow freelytherethrough. The substantially conical shape of the lower portion 16 bdirects the catalyst and/or additive toward the opening 23 in the lowerportion 16 b.

The loading system 10 includes a valve 43 for covering and sealing theopening 23 on a selective basis. The valve 43 can be, for example, aplug valve comprising a seat 44 and plug 45. The seat 44 is secured tothe lower portion 16 b, around the periphery of the opening 23. The plug45 is movable between an upper and a lower position (the plug 45 isdepicted in its lower position in FIG. 1).

The valve 43 is actuated by pressurized air. The pressurized air isdirected to the valve 43 by way of piping 46 that extends through thetransfer pot 18. The flow of pressurized air into the piping 46 can beinitiated and interrupted on a selective basis by a valve 48 in fluidcommunication with the piping 46. The valve 48 a includes an actuator 48a.

The pressurized air impinges upon the plug 45 after exiting of thepiping 46. More particularly, the pressurized air is directed to theinterior of the plug 45, and urges the plug 45 into its closed positionagainst the seat 44. The contact between the plug 45 and the seat 44substantially seals the opening 23.

The plug 45 drops from its closed to its open position when thepressurized air is interrupted by closing the valve 48. The resultinggap between the plug 45 and the seat 44 permits catalyst and/or additivereaching the bottom of the lower portion 16 b to pass through theopening 23 and into the transfer pot 18 (see FIG. 1).

The loading system 10 preferably includes a volume chamber and moisturetrap 49 in fluid communication with the piping 46 (see FIGS. 1 and 2).The volume chamber and moisture trap 49 removes moisture from thepressurized air directed to the valve 43.

The transfer pot 18 comprises a sidewall 51. The sidewall 51 should beof a suitable strength and thickness to withstand pressurization of thetransfer pot 18.

The cross section and overall shape of the transfer pot 18 can vary. Thetransfer pot 18 depicted in the figures has a substantially cylindricalupper portion 18 a, and a substantially conical lower portion 18 b thatadjoins the upper portion 18 a. The upper portion 18 a and the lowerportion 18 b of the transfer pot 18, and the lower portion 16 b of thedust collector 16 define an internal volume 50 within the transfer pot18 (see FIG. 1). (The lower portion 16 b and the valve 43 thus form aboundary between the internal volume 26 of the dust collector 16 and theinternal volume 50 of the transfer pot 18.)

An opening 53 is formed in the center of the lower portion 18 a of thetransfer pot 18. The transfer pot 18 is coupled to the regenerator ofthe FCC unit by piping 54. The piping 54 is in fluid communication withthe opening 53. Catalyst and/or additive enters the piping 54 by way ofthe opening 53 and subsequently flows to the regenerator, as discussedbelow.

A valve 55 having an actuator 55 a is installed in piping 54. The valve55 permits the transfer pot 18 to be isolated from the regenerator on aselective basis. A suitable transfer pot 18 can be obtained, forexample, by adapting a Clemtex, Inc. model 2452 six-cubic footsandblasting pot, or a model 1648 two-cubic-foot sandblasting pot tomate with the dust collector 16. (The sandblasting pot can be mated withthe dust collector 16 by securing the lower portion 16 b of the dustcollector 16 to the upper periphery of the sandblasting pot by asuitable means such as welding.)

The loading unit 14 is supported by a plurality of load cells 56 (seeFIGS. 1 and 4). The load cells 56, as discussed below, provide a measureof the weight of the loading unit 14 in both an unloaded and loadedcondition, i.e., with and without catalyst and/or additive therein. Theload cells 56 are preferably mounted between a base 19 a of the cabinet19, and a plate 57 fixedly coupled to the legs 20 of the transfer pot18.

Each load cell can be restrained from substantial horizontal movement bya corresponding restraint 61 (the restraints 61 are shown only in FIG.5, for clarity.) Each restraint 51 is pivotally coupled to the base 19 aof the cabinet 19.

The loading system 10 can include a plurality of jack assemblies 62 (thejack assemblies 62 are shown only in FIG. 5, for clarity.) Each jackassembly 62 comprises a threaded shaft 62 a fixedly coupled to the base19 a of the cabinet 19. Two nuts 62 b are threadably coupled to eachshaft 62 a. The nuts 62 b are located above and below the plate 57. Thelower nuts 62 b can be raised so that the lower nuts 62 b support theplate 57 (and the portion of the loading system 10 positioned on theplate 57). The upper nuts 62 b can be lowered to lock the plate 57 inposition, i.e., the plate 57 can be sandwiched between the upper andlower nuts 62 b.

The jack assemblies 62 can thus substantially isolate the load cells 57from the weight of the loading system 10. This feature can be used, forexample, to protect the load cells 57 from being damaged by impact loadsduring shipping of the loading system 10.

External connections to the loading unit 14 are preferably configured soas to introduce a negligible tare into the load cell readings. Forexample, the piping 54 includes a flexible sections 46 a thatsubstantially decouples the transfer pot 18 from the portion of thepiping 54 connected to the regenerator, thereby minimizing any tareintroduced into the load cell readings (see FIG. 1). The piping 46likewise includes a flexible section 46 a that substantially decouplesthe transfer pot 18 from the portion of the piping 46 connected to theplant-air equipment. Moreover, the hoses 35, 38 preferably havesufficient flexibility so that any tare introduced thereby isnegligible.

The internal volume 26 of the dust collector 16 and the internal volume50 of the transfer pot 18 are in fluid communication on a selectivebasis by way of piping 58. A valve 59 having an actuator 59 a is locatedin the piping 58 to selectively open and close the path formed by thepiping 58. The piping 58 is used to equalize the pressures within theinternal volumes 26, 50, as discussed below.

The loading system 10 preferably comprises a controller 60 (see FIGS. 3and 6). The actuators 36 a, 42 a, 48 a, 55 a, 59 a of the respectivevalves 36, 42, 48, 55, 59 are electrically coupled to the controller 60.This feature permits the operation of the valves 36, 42, 48, 55, 59 tobe controlled by the controller 60.

The controller 60 is a programmable loop controller (PLC), althoughvirtually any type of computing device such as a minicomputer,microcomputer, etc. can be used as the controller 60 in alternativeembodiments. A server or mainframe computer that controls otherequipment and processes at the refinery in which the loading system 10is operated can also be used to control the loading system 10 in thealternative.

The controller 60 can include a control panel 64 for inputting commandsand operating data to the controller 60 (see FIGS. 3 and 6). Thecontroller 60 and the control panel 64 can be mounted on the cabinet 19.The control panel 64 by itself, or both the control panel 64 and thecontroller 60 can be mounted at a convenient location remote from theremainder of the loading system 10 in alternative embodiments. Forexample, the control panel 64 can be mounted in a central control roomof the refinery, thus allowing the operation of the loading system 10 tobe controlled on a remote basis.

The controller 60 can be configured to cause a predetermined amount ofcatalyst and/or additive to be injected into the regenerator. Thepredetermined amount can be input to the controller 60 by the user viathe control panel 64.

Moreover, the controller 60 can be configured to facilitate injection ofthe catalyst and/or additive on a cyclical basis. For example, thecontroller 60 can be programmed to facilitate the injection of apredetermined amount of additive over a twenty-four hour period, i.e.,per day, using a predetermined number of discrete injections over thatperiod. The operation of the loading system 10 over one such cycle isdescribed below, and is depicted in the form of a flow diagram in FIG.7.

(The controller 60 can also be configured to facilitate injection of thecatalyst and/or additive on a non-cyclical basis. In other words, thecontroller 60 can be programmed to facilitate periodic injections ofvarying amounts of catalyst and/or additive.)

The total amount of catalyst and/or additive to be injected over thetwenty-four hour period can be input to the controller 60 by the userusing the control panel 64. The number of discrete injections to beperformed per day can also be input by way of the control panel 64. (Thecontroller 60 can be programmed to operate based on other inputs inalternative embodiments. For example, the controller 60 can beprogrammed to inject a predetermined amount of additive per cycle, usingpredetermined interval between injections.)

The controller 60 can be programmed to automatically calculate theamount of catalyst and/or additive to be injected during each cyclebased on the above-noted inputs. The controller 60 can also beprogrammed to calculate the time interval between the start of eachinjection. The interval is calculated by dividing twenty-four hours bythe required number of injections per day. Moreover, the controller 60can be configured to accept an input denoting the particular storage bin37 from which the catalyst and/or additive is to be drawn.

The controller 60 sends a control input to the actuator 42 a of thevalve 42 associated with the particular storage bin 37 from which thecatalyst and/or additive is to be drawn (see FIG. 7). The control inputcauses the actuator 42 a to open the valve 42, thereby placing thestorage bin 37 in fluid communication with the dust collector 16. (Thevalves 36, 42, 48, 55, 59 are in their respective closed positions, andthe plug 45 of the valve 43 is in its open (lower) position at the startof the cycle.)

The controller 60 also sends an input to the actuator 36 a of the valve36, thereby allowing pressurized air to flow through the vacuum producer30. The vacuum producer 30 creates a vacuum within the internal volume26 of the dust collector 16 in response to the flow of pressurized airtherethrough, as discussed above.

The vacuum within the internal volume 26 draws the catalyst and/oradditive from the storage bin 37 and into the upper portion 16 a of thedust collector 16. (The direction of travel of the catalyst and/oradditive through the loading system 10 is denoted by arrows 65 in FIG.1.) The catalyst and/or additive subsequently falls toward the lowerportion 16 b due to gravity, and enters the transfer pot 18 by way ofthe opening 23 in the lower portion 16 b, as noted previously.

The controller 60 continually monitors the weight of the loading unit14, and the weight of the catalyst and/or additive added thereto. (Thecombined weight of the loading unit 14 and any catalyst and/or additivetherein is hereinafter referred to as the “live weight” of the loadingsystem 10). In particular, the load cells 56 are electrically coupled tothe controller 60. The controller 60 receives inputs from each of theload cells 56, and adds the inputs to determine the live weight of theloading system 10.

The controller 60 calculates the amount of catalyst and/or additive thatis added to the loading system 10. The controller 60 performs thiscalculation by subtracting the live weight of the loading system 10 at agiven instant from the live weight of the loading system 10 at the startof the cycle, i.e., immediately prior to the opening of the valves 36,42 (the loading unit 14 is assumed to be substantially empty of catalystand/or additive at the start of the cycle).

The controller 60 stops the flow of catalyst and/or additive to the dustcollector 16 as the amount of catalyst and/or additive added to theloading system 10 approaches the amount to be injected into theregenerator during each cycle (this amount is subsequently referred toas a “target value”). In particular, the controller 60 sends a controlinput to the actuator 42 a of the open the valve 42 as the weight of thecatalyst of additive approaches its target value. The control inputcauses the valve 42 to close, thereby interrupting the flow of catalystand/or additive to the dust collector 16. (The controller 60 can beprogrammed to commence the closing of the valve 42 when the weight ofthe catalyst and/or additive is below the target weight by apredetermined amount, so as to compensate for the lag between theissuance of the “close” command to the valve 42, and the point at whichthe valve 42 is fully closed).

The controller 60 also sends a control input to the actuator 36 a of thevalve 36 as the weight of the catalyst of additive in the loading system10 reaches its target value. The control input causes the actuator 36 ato close the valve 36, thereby interrupting the flow of pressurized airthrough the vacuum producer 30.

The controller 60 subsequently sends a control input to the actuator 48a of the valve 48 to cause the valve 48 to open. Opening the valve 48permits pressurized air to enter the internal volume 50 of the transferpot by way of the piping 46. The pressurized air impinges on the plug 45of the valve 43 upon exiting the piping 46, and thereby urges the plug45 into its closed (upper) position against the lower portion 16 b ofthe dust collector 16, as discussed above. The contact between the plug45 and the lower portion 16 b covers and seals the opening 23.

The pressurized air pressurizes the internal volume 50 of the transferpot 18 after the opening 23 has been sealed by the plug 45. (Thepressurized air, as discussed above, is dried by the volume chamber andmoisture trap 49 before reaching the transfer pot 18, thereby minimizingthe potential for contamination of the catalyst and/or additive withinthe transfer pot 18.)

The controller 60 receives an input from a first pressure transducer 68that measures the pneumatic pressure in the internal volume 50 (see FIG.6). The controller 60 also receives an input from a second pressuretransducer 70 that measures the pneumatic pressure in the regeneratorproximate the location at which the catalyst and/or additive isinjected.

The controller 60 sends a control input to the actuator 48 a of thevalve 48 when the difference between the pneumatic pressures in theinternal volume 50 and the regenerator 14 reaches a predetermined value,i.e., when the pressure in the internal volume 50 exceeds the pressurein the regenerator by a predetermined amount. This control input causesthe valve 48 to close.

The controller 60 subsequently sends a control input to the actuator 55a of the valve 55 to cause the valve 55 to open. The differentialbetween the pressures in the internal volume 50 and the regeneratorcauses the catalyst and/or additive in the transfer pot 18 to flow intothe regenerator by way of the piping 54.

The controller 60 sends a control input to the actuator 55 a to closethe valve 55, after a predetermined interval has passed followingissuance of the control input to open the valve 55. (The predeterminedinterval should be chosen so as to allow sufficient time forsubstantially all of the catalyst and/or additive in the transfer pot 18to be injected into the regenerator).

The controller 60 subsequently sends a control input to the actuator 59a of the valve 59 to cause the valve 59 to open. The opening of thevalve 59 permits the pneumatic pressures within the internal volumes 26,50 to substantially equalize. In particular, opening the valve 59relieves the relatively high pressure in the internal volume 50 (whichis approximately equal to pressure within the regenerator 14) by way ofthe piping 58.

The controller 60 sends a control input to the actuator 59 a of thevalve 59 when the pressure differential between the internal volumes 26,50 is approximately zero (the pneumatic pressure in the internal volume26 can be measured by a third pressure transducer 72 located therein).This control input causes the valve 59 to close.

The controller 60 can be programmed to repeat the above process afterthe calculated interval between the start of each injection cycle(discussed above) has passed.

Moreover, the controller 60 can be programmed to inject catalyst and/oradditive from any of the other storage bins 37 after the above-describedcycle has been completed. In other words, another injection cycle can beperformed in a manner identical to that described above, with theexception that the valve 42 associated with one of the other storagebins 37 can be opened to allow the catalyst and/or additive from thatparticular storage bin 37 to be drawn into the dust collector 16.

Vacuuming the catalyst and/or additive directly from its storage bin 37can provide substantial flexibility in the operation of the loadingsystem 10. For example, the loading system 10 can draw catalyst and/oradditive from virtually any location at the refinery accessible by ahose such as the hose 38. Hence, the storage bins 37 can be positionedat an optimal location within the refinery. Moreover, the use of vacuumas a means to transport the catalyst and/or additive to the loadingsystem 10 can permit the catalyst and/or additive to be drawn directlyfrom its shipping container. Hence, the expenditure of time and laborassociated with transferring the catalyst and/or additive from itsshipping container to a storage unit can be eliminated through the useof the loading system 10.

Moreover, vacuuming the catalyst and/or additive directly into the dustcollector 16 can obviate the need to transfer the catalyst and/oradditive into a relatively large storage hopper (as is typicallyrequired with conventional loaders). Hence, the expenditure of time andlabor associated with transferring the catalyst and/or additive to astorage hopper can be eliminated through the use of the loading system10.

Eliminating the need for a storage hopper can also minimize the amountof spaced needed to accommodate the loading system 10. For example, thefootprint the loading system 10 is approximately four feet by four feet,and the maximum height of the loading system is approximately five feet.A conventional loader of comparable capacity (with its storage hopper)can have a footprint of approximately five feet by eight feet, and aheight of approximately twenty feet. (The dimensions of the loadingsystem 10 will vary by application, and specific dimensions are providedherein for exemplary purposes only.) Moreover, in contradistinction tomany conventional loaders, the loading system 10 can be installedwithout the use of special mounting provisions such as a basespecifically tailored to a particular installation.

The loading system 10 can be repositioned with relative ease due to theabsence of a storage hopper. In particular, the absence of a storagehopper provides a measure of portability to the loading system 10, andcan facilitate movement of the loading system 10 between differentlocations within the refinery (or between different refineries) with aminimal expenditure of time and effort in comparison to conventionalloaders. Portability and ease of use for the user of the loading system10 is further enhanced when the loading system 10 is used in conjunctionwith portable storage bins, e.g., known as “totes,” which are normallybuilt to hold approximately 2,000 pounds (approximately 900 kilograms)of catalyst and/or additive.

The absence of a storage hopper, it is believed, can also minimize theamount of time necessary to install the loading system 10 in relation toconventional loaders. The ability to install the loading system 10 in aminimal amount of time can be particularly beneficial, for example,where the use of the loading system 10 is required on an immediate basisto comply with a particular regulatory standard.

The loading system 10 can be used to inject different types of catalystand/or additives with no mechanical reconfiguration, and without theneed to unload and reload a storage hopper. In particular, the loadingsystem 10 can inject one type of catalyst and/or additive from one ofthe storage bins 37, and can immediately thereafter inject another typeof catalyst from another of the storage bins 37 by manipulating thevalves 42 in the appropriate manner. The need for multiple loaders toinject different types of catalyst and/or additives can thus beeliminated through the use of the loading system 10. It is believed thatthat substantial savings in time, labor, refinery space, and money canbe achieved by eliminating the need to purchase, install, and maintainmultiple loaders each dedicated to a particular type of catalyst and/oradditive.

Eliminating the use of a storage hopper can also reduce the amount ofmoisture to which the catalyst and/or additive is exposed. Inparticular, the use of the loading system 10 permits the catalyst and/oradditive to remain in the storage bins 37 until a point immediatelyprior to its injection into the regenerator 14. The environment in thestorage bins 37, it is believed, can be controlled more closely thanthat within a storage hopper. In particular, catalyst and/or additive istypically exposed to plant air when being transported to and stored in ahopper. Plant air is often a source of moisture or other contaminationthat can adversely affect catalyst and/or additive. Hence, minimizingthe exposure of the catalyst and/or additive to plant air, as in theloading system 10, can reduce the potential for contamination of thecatalyst and/or additive.

The pressurized volume loading system 10 is believed to be less that ofconventional loaders of comparable capacity. Hence, less pressurized airis required to operate the loading system 10 in comparison toconventional loaders. This feature can reduce the operating cost of theloading system 10 in relation to conventional loaders.

The loading unit 14 is substantially isolated from sources ofpressurized air as the catalyst and/or additive is transferred thereto,due primarily to the use of a vacuum to transfer the catalyst and/oradditive. Hence, the potential for the readings of the load cells 56 tobe biased by forces induced by pressurized air is believed to beminimal. (Some types of conventional loaders, as discussed above,transfer catalyst and/or additive under pressure from a storage hopperto a transport unit. The pressurized air used effect the transfer canadversely affect readings of the transfer pot's weight.)

The foregoing description is provided for the purpose of explanation andis not to be construed as limiting the invention. While the inventionhas been described with reference to preferred embodiments or preferredmethods, it is understood that the words which have been used herein arewords of description and illustration, rather than words of limitation.Furthermore, although the invention has been described herein withreference to particular structure, methods, and embodiments, theinvention is not intended to be limited to the particulars disclosedherein, as the invention extends to all structures, methods and usesthat are within the scope of the appended claims. Those skilled in therelevant art, having the benefit of the teachings of this specification,may effect numerous modifications to the invention as described herein,and changes may be made without departing from the scope and spirit ofthe invention as defined by the appended claims.

PARTS LIST

-   Loading system 10-   System 11 for storing and loading catalyst and/or additives-   Loading unit 14-   Dust collector 16-   Upper portion 16 a (of dust collector 16)-   Lower portion 16 b-   Sidewall 17 (of dust collector 16)-   Transfer pot 18-   Cabinet 19-   Base 19 a (of cabinet 19)-   Legs 20 (on loading unit 14)-   Opening 23 (in lower portion 16 b)-   Screen 24-   Cover 25-   Internal volume 26 (within dust collector 16)-   Vacuum producer 30-   Filter 32-   Hatch 33 (in dust collector 16)-   Brackets 34-   Hose 35-   Valve 36-   Actuator 36 a (of valve 36)-   Storage bins 37-   Hoses 38-   Arrows 39-   Guide pipes 40-   Valve 42-   Actuator 42 a (of valve 42)-   Valve 43-   Seat 44-   Plug 45 (of valve 43)-   Piping 46-   Flexible section 46 a (of piping 46)-   Valve 48-   Actuator 48 a (of valve 48)-   Volume chamber and moisture trap 49-   Internal volume 50 (within transfer pot 18)-   Sidewall 51 (of transfer pot 18)-   Opening 53 (in lower portion 18 a of transfer pot 18)-   Piping 54-   Flexible section 54 a (of piping 54)-   Valve 55-   Actuator 55 a (of valve 55)-   Load cells 56-   Plate 57-   Piping 58-   Valve 59-   Controller 60-   Brackets 61-   Jack assemblies 62-   Shafts 62 a (of jack assemblies 62)-   Nuts 62 b-   Control panel 64 (of controller 60)-   Arrows 65-   First pressure transducer 68-   Second pressure transducer 70-   Third pressure transducer 72-   Manifold 74

What is claimed is:
 1. A process for introducing catalyst and/oradditives into a fluidized catalytic cracking unit, comprising:generating a vacuum within a loading unit; drawing one of the catalystand/or additives from a storage bin and into the loading unit inresponse to the vacuum wherein drawing one of the catalyst and/oradditives from a storage bin and into the loading unit in response tothe vacuum comprises opening a valve to place the storage bin in fluidcommunication with the loading unit; drawing another catalyst and/oradditive from another storage bin and into the loading unit in responseto the vacuum by opening another valve to place the another storage binin fluid communication with the loading unit; monitoring the weight ofthe catalyst and/or additives drawn into the loading unit and stoppinggeneration of the vacuum when the weight reaches a predetermined value;pressurizing the loading unit; and injecting the catalyst and/oradditives into the fluidized catalytic cracking unit in response to thepressurization of the loading unit.
 2. The process of claim 1, whereingenerating a vacuum within a unit comprises initiating a flow ofpressurized air through a vacuum producer in fluid communication withthe loading unit.
 3. The process of claim 1, wherein injecting the oneof the catalyst and/or additives into the fluidized catalytic crackingunit in response to the pressurization of the loading unit comprisesinjecting the one of the catalyst and/or additive into a regenerator ofthe fluidized catalytic cracking unit.
 4. The process of claim 1,wherein pressurizing the loading unit comprises opening a valve to placethe loading unit in fluid communication with a source of pressurizedair.
 5. The process of claim 1, wherein generating a vacuum within aunit and drawing one of the catalyst and/or additives from a storage binand into the loading unit in response to the vacuum comprises generatingthe vacuum in a dust collector of the loading unit and drawing one ofthe catalyst and/or additives from a storage bin and into the dustcollector in response to the vacuum.
 6. The process of claim 1, whereinpressurizing the loading unit and injecting the one of the catalystand/or additives into the fluidized catalytic cracking unit in responseto the pressurization of the loading unit comprises pressurizing atransfer pot of the loading unit and injecting the one of the catalystand/or additives into the fluidized catalytic cracking unit from thetransfer pot.
 7. A process for introducing at least two catalysts and/oradditives into a fluidized catalytic cracking unit, each of said atleast two catalysts and/or additives being stored in separate storagebins, the process comprising: generating a vacuum within a loading unit;opening a first valve to place a first storage bin holding one of the atleast two catalysts and/or additives in fluid communication with theloading unit to draw the catalyst or additive from the first storage binand into the loading unit in response to the vacuum; opening a secondvalve to place a second storage bin holding at least one other catalystor additive in fluid communication with the loading unit to draw thecatalyst or additive from the second storage bin and into the loadingunit in response to the vacuum; pressurizing the loading unit; andinjecting the catalyst and/or additive from the loading unit into thefluidized catalytic cracking unit in response to the pressurization ofthe loading unit.
 8. The process of claim 7 further comprisingmonitoring the weight of each of the at least two catalysts and/oradditives drawn into the loading unit, and stopping the drawing of eachof said catalyst and/or additive when the weight of the catalyst and/oradditive drawn into the loading unit reaches a predetermined level. 9.The process of claim 7, wherein pressurizing the loading unit andinjecting the catalyst and/or additives into the fluidized catalyticcracking unit in response to the pressurization of the loading unitcomprises pressurizing a transfer pot of the loading unit and injectingthe catalyst and/or additives into the fluidized catalytic cracking unitfrom the transfer pot.